1934. Cratogeomys castanops tamaulipensis Nelson and Goldman, Proc. Biol. Soc. Washington, 47:141, June 13, type from Matamoros, Tamaulipas.
Distribution in Tamaulipas.—Known only from two localities in extreme northern part of state, but probably occurs throughout northeastern part of state.
Three specimens from three miles southeast of Reynosa are referred to C. c. tamaulipensis on geographic grounds. They are tawny brown dorsally instead of cinnamon brown or pinkish cinnamon as Nelson and Goldman (1943:141) described tamaulipensis, and the basioccipital bone (in one male) is parallel-sided instead of wedge-shaped. Possibly this difference is owing to sex; Nelson and Goldman studied only one adult, a female (the type), and the only adult seen by me was a male.
Measurements.—An adult male (58118) from three miles southeast of Reynosa, measured as follows: 301; 81; 40; 7; condylobasal length, 57.0; zygomatic breadth, 41.2; palatal length, 36.1; breadth of rostrum, 11.8; length of nasals, 22.0; squamosal breadth, 34.0; alveolar length of maxillary tooth-row, 10.8.
Records of occurrence.—Specimens examined, 3, from 3 mi. SE Reynosa.
Additional record: Matamoros (Nelson and Goldman, 1934:140).
Perognathus merriami merriami J. A. Allen
Merriam's Pocket Mouse
1892. Perognathus merriami J. A. Allen, Bull. Amer. Mus. Nat. Hist., 4:45, March 25, type from Brownsville, Cameron Co., Texas.
Distribution in Tamaulipas.—State-wide except southwestern part.
Most of the available specimens of P. m. merriami were collected in the semi-arid areas of mesquite and grasses. At Soto la Marina P. m. merriami was abundant in open fields surrounded by brush. One female, collected on July 4, one mile south of Altamira was lactating. Weights of 16 adults from Soto la Marina and that of nine adults from the vicinity of San Fernando are, respectively: 8.2 (7-10) and 8.1 (7-9) grams.